Doppler radars, such as those used in active radar guided missiles and the like, are highly vulnerable to deception jamming systems, which systems send signals to the radar receiver which appear to be return signals from a target. If these apparent targets or deception signals cannot be differentiated from true target return signals the target may slip away virtually undetected. Generally, the jamming signal is swept through a range of frequencies to simulate a moving target which the doppler radar will detect and instruct the guided missile or the like to follow. Some semiactive guided missiles and radars sense excessive acceleration in return signals and reject them as deception jamming signals. However, if the deception jamming signals are swept relatively slowly, these prior art radars cannot detect the signals as deception jamming signals.